Fault tolerant device upgrade

ABSTRACT

A technology is directed to embedded device updates. In one example of the technology, a partition of a memory is atomically updated. The partition includes partition tables including a primary partition table and a back-up partition table. The partition tables include entries for the images included in the partition, and information associated with the images included in the partition. Atomically updating the partition of the memory includes writing an updated version to the partition. The written updated version is verified. An updated partition table is written to the back-up partition table. The updated partition table is written to the primary partition table. If it is determined that a power, or other, fault occurred while the primary partition table was being written, the primary partition table is overwritten with the back-up partition table.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. Provisional Pat. App. No.62/669,327, filed May 9, 2018, entitled “POWER FAULT TOLERANT DEVICEUPGRADE”. The entirety of this afore-mentioned application isincorporated herein by reference.

BACKGROUND

The Internet of Things (“IoT”) generally refers to a system of devicescapable of communicating over a network. The devices can includeeveryday objects such as toasters, coffee machines, thermostat systems,washers, dryers, lamps, automobiles, and the like. The networkcommunications can be used for device automation, data capture,providing alerts, personalization of settings, and numerous otherapplications.

SUMMARY OF THE DISCLOSURE

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

Briefly stated, the disclosed technology is generally directed toembedded device updates. In one example of the technology, a partitionof a memory is atomically updated. In some examples, the partitionincludes partition tables including a primary partition table and aback-up partition table. In some examples, the partition tables includeentries for the images included in the partition, and informationassociated with the images included in the partition. In some examples,atomically updating the partition of the memory includes writing anupdated version to the partition. In some examples, the written updatedversion is verified. In some examples, an updated partition table iswritten to the back-up partition table. In some examples, the updatedpartition table is written to the primary partition table. In someexamples, if it is determined that a power, or other, fault occurredwhile the primary partition table was being written, the primarypartition table is overwritten with the back-up partition table.

Other aspects of and applications for the disclosed technology will beappreciated upon reading and understanding the attached figures anddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive examples of the present disclosure aredescribed with reference to the following drawings. In the drawings,like reference numerals refer to like parts throughout the variousfigures unless otherwise specified. These drawings are not necessarilydrawn to scale.

For a better understanding of the present disclosure, reference will bemade to the following Detailed Description, which is to be read inassociation with the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating one example of a suitableenvironment in which aspects of the technology may be employed;

FIG. 2 is a block diagram illustrating one example of a suitablecomputing device according to aspects of the disclosed technology;

FIG. 3 is a block diagram illustrating an example of a system;

FIG. 4 is a block diagram illustrating an example of the devicecontroller of FIG. 3; and

FIGS. 5A-5B are a flow diagram illustrating an example process inaccordance with aspects of the present disclosure.

DETAILED DESCRIPTION

The following description provides specific details for a thoroughunderstanding of, and enabling description for, various examples of thetechnology. One skilled in the art will understand that the technologymay be practiced without many of these details. In some instances,well-known structures and functions have not been shown or described indetail to avoid unnecessarily obscuring the description of examples ofthe technology. It is intended that the terminology used in thisdisclosure be interpreted in its broadest reasonable manner, even thoughit is being used in conjunction with a detailed description of certainexamples of the technology. Although certain terms may be emphasizedbelow, any terminology intended to be interpreted in any restrictedmanner will be overtly and specifically defined as such in this DetailedDescription section. Throughout the specification and claims, thefollowing terms take at least the meanings explicitly associated herein,unless the context dictates otherwise. The meanings identified below donot necessarily limit the terms, but merely provide illustrativeexamples for the terms. For example, each of the terms “based on” and“based upon” is not exclusive, and is equivalent to the term “based, atleast in part, on”, and includes the option of being based on additionalfactors, some of which may not be described herein. As another example,the term “via” is not exclusive, and is equivalent to the term “via, atleast in part”, and includes the option of being via additional factors,some of which may not be described herein. The meaning of “in” includes“in” and “on.” The phrase “in one embodiment,” or “in one example,” asused herein does not necessarily refer to the same embodiment orexample, although it may. Use of particular textual numeric designatorsdoes not imply the existence of lesser-valued numerical designators. Forexample, reciting “a widget selected from the group consisting of athird foo and a fourth bar” would not itself imply that there are atleast three foo, nor that there are at least four bar, elements.References in the singular are made merely for clarity of reading andinclude plural references unless plural references are specificallyexcluded. The term “or” is an inclusive “or” operator unlessspecifically indicated otherwise. For example, the phrases “A or B”means “A, B, or A and B.” As used herein, the terms “component” and“system” are intended to encompass hardware, software, or variouscombinations of hardware and software. Thus, for example, a system orcomponent may be a process, a process executing on a computing device,the computing device, or a portion thereof.

Briefly stated, the disclosed technology is generally directed toembedded device updates. In one example of the technology, a partitionof a memory is atomically updated. In some examples, the partitionincludes partition tables including a primary partition table and aback-up partition table. In some examples, the partition tables includeentries for the images included in the partition, and informationassociated with the images included in the partition. In some examples,atomically updating the partition of the memory includes writing anupdated version to the partition. In some examples, the written updatedversion is verified. In some examples, an updated partition table iswritten to the back-up partition table. In some examples, the updatedpartition table is written to the primary partition table. In someexamples, a boot health check is performed. In some examples, if it isdetermined that a power fault or other failure occurred while theprimary partition table was being written, the primary partition tableis overwritten with the back-up partition table.

In some examples, an embedded device upgrade is performed in such a wayas to at least be tolerant to power faults and/or failures, and inconditions in which available storage may be limited. For example, thetechnology may also be tolerant to crash faults, “fail-stop” faults,execution failures, and/or the like. The embedded device may be dividedinto several partitions, which may be physical partitions and/or logicalpartitions. In some examples, each partition is updated atomically. Anupdate may encompass multiple partitions.

Partition tables may be used to ensure that the atomic updating of thepartition is performed in a manner that is failure tolerant. In someexamples, there are two partition tables in each partition, a primarypartition table and a back-up partition table. In some examples, eachpartition table has an entry for each image on the partition, andincluding information about each image, such as, in some examples, theoffset of the image in memory.

The new version to be updated may be written into memory and thenverified. The partition table may then be updated to be based on theupdated version, and the updated version then then be written to thebackup partition table. The updated table may then be written to theprimary partition table. A boot health check may then be performed. Insome examples, if the boot health check fails, indicating that a powerfault and/or other failure occurred while the primary partition tablewas being written, then the primary partition table is overwritten withthe backup partition table.

Many variations to the upgrade process may be performed in variousexamples. For instance, the upgrade process may be further modified tobe not just failure tolerant, but to also be tolerant to corruption.Also, another variation may allow the upgrade progress to be used whenthere is insufficient free space available. Example variations arediscussed in greater detail below.

Illustrative Devices/Operating Environments

FIG. 1 is a diagram of environment 100 in which aspects of thetechnology may be practiced. As shown, environment 100 includescomputing devices 110, as well as network nodes 120, connected vianetwork 130. Even though particular components of environment 100 areshown in FIG. 1, in other examples, environment 100 can also includeadditional and/or different components. For example, in certainexamples, the environment 100 can also include network storage devices,maintenance managers, and/or other suitable components (not shown).Computing devices 110 shown in FIG. 1 may be in various locations,including on premise, in the cloud, or the like. For example, computerdevices 110 may be on the client side, on the server side, or the like.

As shown in FIG. 1, network 130 can include one or more network nodes120 that interconnect multiple computing devices 110, and connectcomputing devices 110 to external network 140, e.g., the Internet or anintranet. For example, network nodes 120 may include switches, routers,hubs, network controllers, or other network elements. In certainexamples, computing devices 110 can be organized into racks, actionzones, groups, sets, or other suitable divisions. For example, in theillustrated example, computing devices 110 are grouped into three hostsets identified individually as first, second, and third host sets 112a-112 c. In the illustrated example, each of host sets 112 a-112 c isoperatively coupled to a corresponding network node 120 a-120 c,respectively, which are commonly referred to as “top-of-rack” or “TOR”network nodes. TOR network nodes 120 a-120 c can then be operativelycoupled to additional network nodes 120 to form a computer network in ahierarchical, flat, mesh, or other suitable types of topology thatallows communications between computing devices 110 and external network140. In other examples, multiple host sets 112 a-112 c may share asingle network node 120. Computing devices 110 may be virtually any typeof general- or specific-purpose computing device. For example, thesecomputing devices may be user devices such as desktop computers, laptopcomputers, tablet computers, display devices, cameras, printers, orsmartphones. However, in a data center environment, these computingdevices may be server devices such as application server computers,virtual computing host computers, or file server computers. Moreover,computing devices 110 may be individually configured to providecomputing, storage, and/or other suitable computing services.

In some examples, one or more of the computing devices 110 is an IoTdevice, a device that comprises part or all of an IoT support service, adevice comprising part or all of an application back-end, or the like,as discussed in greater detail below.

Illustrative Computing Device

FIG. 2 is a diagram illustrating one example of computing device 200 inwhich aspects of the technology may be practiced. Computing device 200may be virtually any type of general- or specific-purpose computingdevice. For example, computing device 200 may be a user device such as adesktop computer, a laptop computer, a tablet computer, a displaydevice, a camera, a printer, or a smartphone. Likewise, computing device200 may also be server device such as an application server computer, avirtual computing host computer, or a file server computer, e.g.,computing device 200 may be an example of computing device 110 ornetwork node 120 of FIG. 1. Computing device 200 may also be an IoTdevice that connects to a network to receive IoT services. Likewise,computer device 200 may be an example any of the devices illustrated inor referred to in FIGS. 3-5, as discussed in greater detail below. Asillustrated in FIG. 2, computing device 200 includes processing circuit210, operating memory 220, memory controller 230, data storage memory250, input interface 260, output interface 270, and network adapter 280.Each of these afore-listed components of computing device 200 includesat least one hardware element.

Computing device 200 includes at least one processing circuit 210configured to execute instructions, such as instructions forimplementing the herein-described workloads, processes, or technology.Processing circuit 210 may include a microprocessor, a microcontroller,a graphics processor, a coprocessor, a field-programmable gate array, aprogrammable logic device, a signal processor, or any other circuitsuitable for processing data. Processing circuit 210 is an example of acore. The aforementioned instructions, along with other data (e.g.,datasets, metadata, operating system instructions, etc.), may be storedin operating memory 220 during run-time of computing device 200.Operating memory 220 may also include any of a variety of data storagedevices/components, such as volatile memories, semi-volatile memories,random access memories, static memories, caches, buffers, or other mediaused to store run-time information. In one example, operating memory 220does not retain information when computing device 200 is powered off.Rather, computing device 200 may be configured to transfer instructionsfrom a non-volatile data storage component (e.g., data storage component250) to operating memory 220 as part of a booting or other loadingprocess. In some examples, other forms of execution may be employed,such as execution directly from data storage component 250, e.g.,eXecute In Place (XIP).

Operating memory 220 may include 4^(th) generation double data rate(DDR4) memory, 3^(rd) generation double data rate (DDR3) memory, otherdynamic random access memory (DRAM), High Bandwidth Memory (HBM), HybridMemory Cube memory, 3D-stacked memory, static random access memory(SRAM), magnetoresistive random access memory (MRAM), pseudorandomrandom access memory (PSRAM), or other memory, and such memory maycomprise one or more memory circuits integrated onto a DIMM, SIMM,SODIMM, Known Good Die (KGD), or other packaging. Such operating memorymodules or devices may be organized according to channels, ranks, andbanks. For example, operating memory devices may be coupled toprocessing circuit 210 via memory controller 230 in channels. Oneexample of computing device 200 may include one or two DIMMs perchannel, with one or two ranks per channel. Operating memory within arank may operate with a shared clock, and shared address and commandbus. Also, an operating memory device may be organized into severalbanks where a bank can be thought of as an array addressed by row andcolumn. Based on such an organization of operating memory, physicaladdresses within the operating memory may be referred to by a tuple ofchannel, rank, bank, row, and column.

Despite the above-discussion, operating memory 220 specifically does notinclude or encompass communications media, any communications medium, orany signals per se.

Memory controller 230 is configured to interface processing circuit 210to operating memory 220. For example, memory controller 230 may beconfigured to interface commands, addresses, and data between operatingmemory 220 and processing circuit 210. Memory controller 230 may also beconfigured to abstract or otherwise manage certain aspects of memorymanagement from or for processing circuit 210. Although memorycontroller 230 is illustrated as single memory controller separate fromprocessing circuit 210, in other examples, multiple memory controllersmay be employed, memory controller(s) may be integrated with operatingmemory 220, or the like. Further, memory controller(s) may be integratedinto processing circuit 210. These and other variations are possible.

In computing device 200, data storage memory 250, input interface 260,output interface 270, and network adapter 280 are interfaced toprocessing circuit 210 by bus 240. Although, FIG. 2 illustrates bus 240as a single passive bus, other configurations, such as a collection ofbuses, a collection of point to point links, an input/output controller,a bridge, other interface circuitry, or any collection thereof may alsobe suitably employed for interfacing data storage memory 250, inputinterface 260, output interface 270, or network adapter 280 toprocessing circuit 210.

In computing device 200, data storage memory 250 is employed forlong-term non-volatile data storage. Data storage memory 250 may includeany of a variety of non-volatile data storage devices/components, suchas non-volatile memories, disks, disk drives, hard drives, solid-statedrives, or any other media that can be used for the non-volatile storageof information. However, data storage memory 250 specifically does notinclude or encompass communications media, any communications medium, orany signals per se. In contrast to operating memory 220, data storagememory 250 is employed by computing device 200 for non-volatilelong-term data storage, instead of for run-time data storage. In someexamples, performance counter 475 may also be configured to measurelatency from a core to a target, such as from MCU 462 to SRAM 458.

Also, computing device 200 may include or be coupled to any type ofprocessor-readable media such as processor-readable storage media (e.g.,operating memory 220 and data storage memory 250) and communicationmedia (e.g., communication signals and radio waves). While the termprocessor-readable storage media includes operating memory 220 and datastorage memory 250, the term “processor-readable storage media,”throughout the specification and the claims whether used in the singularor the plural, is defined herein so that the term “processor-readablestorage media” specifically excludes and does not encompasscommunications media, any communications medium, or any signals per se.However, the term “processor-readable storage media” does encompassprocessor cache, Random Access Memory (RAM), register memory, and/or thelike.

Computing device 200 also includes input interface 260, which may beconfigured to enable computing device 200 to receive input from users orfrom other devices. In addition, computing device 200 includes outputinterface 270, which may be configured to provide output from computingdevice 200. In one example, output interface 270 includes a framebuffer, graphics processor, graphics processor or accelerator, and isconfigured to render displays for presentation on a separate visualdisplay device (such as a monitor, projector, virtual computing clientcomputer, etc.). In another example, output interface 270 includes avisual display device and is configured to render and present displaysfor viewing. In yet another example, input interface 260 and/or outputinterface 270 may include a universal asynchronous receiver/transmitter(“UART”), a Serial Peripheral Interface (“SPI”), Inter-IntegratedCircuit (“I2C”), a General-purpose input/output (GPIO), and/or the like.Moreover, input interface 260 and/or output interface 270 may include orbe interfaced to any number or type of peripherals.

In the illustrated example, computing device 200 is configured tocommunicate with other computing devices or entities via network adapter280. Network adapter 280 may include a wired network adapter, e.g., anEthernet adapter, a Token Ring adapter, or a Digital Subscriber Line(DSL) adapter. Network adapter 280 may also include a wireless networkadapter, for example, a Wi-Fi adapter, a Bluetooth adapter, a ZigBeeadapter, a Long Term Evolution (LTE) adapter, SigFox, LoRa, Powerline,or a 5G adapter.

Although computing device 200 is illustrated with certain componentsconfigured in a particular arrangement, these components and arrangementare merely one example of a computing device in which the technology maybe employed. In other examples, data storage memory 250, input interface260, output interface 270, or network adapter 280 may be directlycoupled to processing circuit 210, or be coupled to processing circuit210 via an input/output controller, a bridge, or other interfacecircuitry. Other variations of the technology are possible.

Some examples of computing device 200 include at least one memory (e.g.,operating memory 220) adapted to store run-time data and at least oneprocessor (e.g., processing unit 210) that is adapted to executeprocessor-executable code that, in response to execution, enablescomputing device 200 to perform actions.

Illustrative Systems

Some examples of the disclosure are used in the context of a multi-coremicrocontroller included in an IoT device that operates as a devicecontroller for an IoT device. Examples of the disclosure may also beused in other suitable contexts. A particular example of the disclosureused in the context of a multi-core microcontroller included in an IoTdevice that operates as a device controller for an IoT device isdiscussed below with regard to FIG. 4 and FIG. 5.

FIG. 3 is a block diagram illustrating an example of a system (300).System 300 may include network 330, as well as IoT support service 351,IoT devices 341 and 342, and application back-end 313, which all connectto network 330.

The term “IoT device” refers to a device intended to make use of IoTservices. An IoT device can include virtually any device that connectsto a network to use IoT services, including for telemetry collection orany other purpose. IoT devices include any devices that can connect to anetwork to make use of IoT services. In various examples, IoT devicesmay communicate with a cloud, with peers or local system or acombination or peers and local systems and the cloud, or in any othersuitable manner. IoT devices can include everyday objects such astoasters, coffee machines, thermostat systems, washers, dryers, lamps,automobiles, and the like. IoT devices may also include, for example, avariety of devices in a “smart” building including lights, temperaturesensors, humidity sensors, occupancy sensors, and the like. The IoTservices for the IoT devices can be used for device automation, datacapture, providing alerts, personalization of settings, and numerousother applications.

The term “IoT support service” refers to a device, a portion of at leastone device, or multiple devices such as a distributed system, to which,in some examples, IoT devices connect on the network for IoT services.In some examples, the IoT support service is an IoT hub. In someexamples, the IoT hub is excluded, and IoT devices communicate with anapplication back-end, directly or through one or more intermediaries,without including an IoT hub, and a software component in theapplication back-end operates as the IoT support service. IoT devicesreceive IoT services via communication with the IoT support service. Insome examples, an IoT support service may be embedded inside of adevice, or in local infrastructure.

Application back-end 313 refers to a device, or multiple devices such asa distributed system, that performs actions that enable data collection,storage, and/or actions to be taken based on the IoT data, includinguser access and control, data analysis, data display, control of datastorage, automatic actions taken based on the IoT data, and/or the like.Application back-end 313 could also be one or more virtual machinesdeployed in a public or a private cloud. In some examples, at least someof the actions taken by the application back-end may be performed byapplications running in application back-end 313.

Each of the IoT devices 341 and 342 and/or the devices that comprise IoTsupport service 351 and/or application back-end 313 may include examplesof computing device 200 of FIG. 2. The term “IoT support service” is notlimited to one particular type of IoT service, but refers to the deviceto which the IoT device communicates, after provisioning, for at leastone IoT solution or IoT service. That is, the term “IoT supportservice,” as used throughout the specification and the claims, isgeneric to any IoT solution. The term IoT support service simply refersto the portion of the IoT solution/IoT service to which provisioned IoTdevices communicate. In some examples, communication between IoT devicesand one or more application back-ends occur with an IoT support serviceas an intermediary. FIG. 3 and the corresponding description of FIG. 3in the specification illustrates an example system for illustrativepurposes that does not limit the scope of the disclosure.

One or more of the IoT devices 341 and 342 may include device controller345, which may operate to control the IoT device. Each device controller345 may include multiple execution environments. Device controller 345may be a multi-core microcontroller. In some examples, device controller345 is an integrated circuit with multiple cores, such as at least onecentral processing unit (CPU) and at least one microcontroller (MCU).

Network 330 may include one or more computer networks, including wiredand/or wireless networks, where each network may be, for example, awireless network, local area network (LAN), a wide-area network (WAN),and/or a global network such as the Internet. On an interconnected setof LANs, including those based on differing architectures and protocols,a router acts as a link between LANs, enabling messages to be sent fromone to another. Also, communication links within LANs typically includetwisted wire pair or coaxial cable, while communication links betweennetworks may utilize analog telephone lines, full or fractionaldedicated digital lines including T1, T2, T3, and T4, IntegratedServices Digital Networks (ISDNs), Digital Subscriber Lines (DSLs),wireless links including satellite links, or other communications linksknown to those skilled in the art. Furthermore, remote computers andother related electronic devices could be remotely connected to eitherLANs or WANs via a modem and temporary telephone link. Network 330 mayinclude various other networks such as one or more networks using localnetwork protocols such as 6LoWPAN, ZigBee, or the like. Some IoT devicesmay be connected to a user device via a different network in network 330than other IoT devices. In essence, network 330 includes anycommunication method by which information may travel between IoT supportservice 351, IoT devices 341 and 342, and application back-end 313.Although each device or service is shown connected as connected tonetwork 330, that does not mean that each device communicates with eachother device shown. In some examples, some devices/services shown onlycommunicate with some other devices/services shown via one or moreintermediary devices. Also, although network 330 is illustrated as onenetwork, in some examples, network 330 may instead include multiplenetworks that may or may not be connected with each other, with some ofthe devices shown communicating with each other through one network ofthe multiple networks and other of the devices shown communicating witheach other with a different network of the multiple networks.

As one example, IoT devices 341 and 342 are devices that are intended tomake use of IoT services provided by IoT support service 351.

Device updates for IoT devices such as IoT devices 341 and 342 may occurat various times. For example, applications, other software, and/orfirmware on an IoT device may be updated. Updates may be communicated tothe IoT devices (e.g., 341 and 342) from the IoT support service (e.g.,IoT support service 351 or application back-end 313 or the like) vianetwork 330. The IoT devices may be configured to perform updates in amanner that is tolerant to power faults and other failures.

System 300 may include more or less devices than illustrated in FIG. 3,which is shown by way of example only.

Illustrative Device

FIG. 4 is a block diagram illustrating an example of device controller445. Device controller 445 may be employed as an example of devicecontroller 345 of FIG. 3. Device controller 445 may include securitycomplex 451, CPU 453, direct memory access (DMA) block 454, trust zone(TZ) DMA block 455, Flash memory 456, Radio block 457, secure staticrandom access memory (SRAM) 458, Interfaces 459, MCU 461, MCU 462,primary advanced extensible interface (AXI) bus 463, secondary AXI bus464, bridges 465 and 466, AXI to advanced peripheral bus (APB) bridgesper peripheral 467, Interfaces 471, GPIOs 472, analog-to-digitalconverter (ADC) 473, real-time clock (RTC) 474, and performance counter475.

In some examples, device controller 445 enables a device in which devicecontroller 445 is included to operate as an IoT device, such as IoTdevice 341 or 342 of FIG. 3. In some examples, device controller 445 isa multi-core microcontroller. In some examples, device controller 445runs a high-level operating system. In some examples, device controller445 may have at least 4 MB of RAM and at least 4 MB of flash memory, andmay be a single integrated circuit. In some examples, device controller445 provides not just network connectivity, but various other functionsincluding hardware and software security, a monitored operating system,cryptographic functions, peripheral control, telemetry, and/or the like.In addition, device controller 445 may include technology for allowingdevice controller 445 to be booted in a secure manner, allowing devicecontroller 445 to be securely updated, ensuring that proper software isrunning on device controller 445, allowing device controller 445 tofunction correctly as an IoT device, and/or the like.

In some examples, security complex 451 include a core security complex(CSC) that is the hardware root of trust in device controller 445. Insome examples, the core security complex is directly connected to thesecure MCU in security complex 451. In some examples, the secure MCU insecurity complex 451 has a very high degree of trust, but is lesstrusted than the core security complex in security complex 451. In someexamples, security complex 451 brings up the full system at boot.

In some examples, CPU 453 runs a high-level operating system. In someexamples, CPU 453 has two independent execution environments: a SecureWorld execution environment and a Normal World execution environment.The term “secure world” is used broadly to refer to a trustedenvironment and is not limited to a particular security feature. In someexamples, the Secure World execution environment of CPU 453 is also partof the trusted computing base of the system. For instance, in someexamples, the Secure World execution environment of CPU 453 hasunfettered access to reprogram hardware protection mechanisms, such asfirewalls in some examples. In some examples, the Secure World executionenvironment of CPU 453 does not, however, have access to the internalsof the core security complex of security complex 451 and relies on thesecure MCU of security complex 451 for particular security-sensitiveoperations.

Radio block 457 may provide Wi-Fi communication. Primary AXI bus 463 andsecondary AXI bus 464 may be buses that connect the components shown. Insome examples, bridges 465, 466, and 467 bridge the components shown.RTC block 474 may operate as a real-time clock. In some examples, allcomponents in device controller 345 can read from the RTC block 474, butnot all components have write access to RTC block 474. Device controller445 may include various forms of memory, including flash and SRAM, suchas flash memory 456 and secure SRAM 458.

In some examples, IO Subsystem 1 461 and IO Subsystem 2 462 are I/Osubsystems for general purpose I/O connectivity. In some examples, IOSubsystem 1 461 and IO Subsystem 2 462 each include an MCU.

DMA block 454 may be used to manage data movement for the Normal Worldexecution environment of CPU 453. Trust zone (TZ) DMA block 455 may beused to manage data movement for the Secure World execution environmentof CPU 453. In some examples, each IO subsystem also has its own DMAblock. Each of the DMA blocks may be configured to support data movementbetween cores, peripherals, other components, and/or the like.

Each of the cores may have bi-directional mailboxes to supportinter-processor communication. Performance counter 475 may be configuredto count read requests, write requests, and data type requests forperformance monitoring. In some examples, performance counter 475 mayalso be configured to measure latency from a core to a target, such asfrom MCU 462 to SRAM 458.

In some examples, the interfaces at block 459 include twoInter-integrated circuit Sound (I2S) interfaces: one for audio input andone for audio output. In other examples, other configurations ofinterfaces may be employed, and block 459 may include any suitableinterfaces in various examples.

In some examples, the MCU in security complex 451 has a very high degreeof trust, but is less trusted than the core security complex in securitycomplex 451. In these examples, the MCU in security complex 451 controlsone or more functions associated with a very high degree of trust. Inone example, the MCU in security complex 451 controls power for devicecontroller 445 and/or an IoT device.

In some examples, the Secure World execution environment of CPU 453 isalso part of the trusted computing base of the system. For instance, insome examples, the Secure World runtime of CPU 453 (Secure World RT) hasunfettered access to reprogram hardware protection mechanisms, such asfirewalls in some examples. In some examples, Secure World RT does not,however, have access to the internals of the core security complex ofsecurity complex 451 and relies on the MCU in security complex 451 forparticular security-sensitive operations.

The Normal World execution environment of CPU 453 may be configured tohave limited access to such on-chip resources such as memories. In someexamples, various security and quality standards (e.g., relatively highstandards) may be enforced for code running in this environment but isless trusted than either the code running on the MCU in security complex451 or the code running in the Secure World of CPU 453.

In some examples, MCUs 461 and 462 are less trusted than the MCU insecurity complex 451 and less trusted than CPU 453. In some examples,Radio block 457 may include a core, which may be an MCU in someexamples. Radio block 457 may provide Wi-Fi functionality andconnectivity to the Internet and cloud services such as IoT services. Insome examples, Radio block 457 may provide communications via Bluetooth,Near Field Communication (NFC), ZigBee, Long-Term Evolution (LTE),and/or other connectivity technology. In some examples, the core inRadio block 457 does not have any access to unencrypted secrets, and isnot capable of compromising the execution of CPU 453.

In some examples, each independent execution environment is managed by asingle software component executing in a separate execution environmentthat is referred to the “parent” of the execution environment. In suchexamples, one exception may be that the hardware root of trust (the coresecurity complex of security complex 451 in this example) has no parent.In one particular example, each parent executes in an environment thatis at least as trusted as the environments it manages. In otherexamples, other suitable means of security may be employed. Managementoperations may include booting and resuming the target environment,monitoring and handling resets in the target environment, andconfiguring access policy for the target environment. In some cases,certain management operations are performed by a component other than aparent. For instance, in some examples, the Normal World of CPU 453 isthe environment that manages MCUs 461 and 462, but receives assistancefrom the Secure World of CPU 453 to do so.

For instance, in some examples, the MCU of security complex 451 managesSecure World RT of CPU 453, a component in Secure World RT in CPU 453manages Normal World OS of CPU 453, a component in the Normal World OSof CPU 453 manages Normal World user-mode of CPU 453, and Normal Worlduser-mode services of CPU 453 manages the MCUs 461 and 462 and the corein Radio block 457.

In some examples, not only are independent execution environmentsmanaged by a software component from a more trusted executionenvironment, but different functions are assigned to the differentindependent execution environments, with more sensitive functionsassigned to more trusted independent execution environments. In oneparticular example, independent execution environments less trusted thanthe independent execution environment to which it is assigned arerestricted from having access to the function. In this way, in someexamples, the independent execution environments achievedefense-in-depth based on a hierarchy of trust.

For instance, in some examples, the core security complex of securitycomplex 451 is at the top of the hierarchy and is assigned to secrets(e.g., encryption keys), the secure MCU in core security complex 451 isnext in the hierarchy and is assigned to controlling power, Secure WorldRT of CPU 453 is next in the hierarchy and is assigned to storage and towrite access to a real time clock (RTC), Normal World OS of CPU 453 isnext in the hierarchy and is assigned to Wi-Fi, Normal World user-modeapplications of CPU 453 is next in the hierarchy and is assigned toapplications, and the MCUs 461 and 462 are at the bottom of thehierarchy and are assigned to peripherals. In other examples, functionsare assigned to independent execution environments in a differentmanner.

In some examples, each level of the hierarchy of trust, except for thebottom (i.e., least trusted) level of the hierarchy, has control overaccepting or rejecting requests from a less trusted level, e.g., interms of implementing support for the software they handle, and have theability to rate limit or audit the requests from less trusted levels,and to validate requests from lower levels, e.g., to ensure that therequests correct and true. Also, as previously discussed, in someexamples, each level of hierarchy except the top (i.e., most trusted)level has a parent that is responsible for managing the lower (i.e.,less trusted) level, including monitoring whether the software on thelower level is running correctly.

Some examples of device controller 455 may be a multi-coremicroprocessor that includes, for example, at least one CPU and at leastone microcontroller, in addition to flash memory with multiple banks aspreviously discussed. In some examples, the multi-core processor may bean integrated circuit with multiple cores. In some examples, themulti-core processor may be used to provide functionality for aconnected device. In some examples, device controller 455 may providenetwork connectivity to the connected device, and may also providevarious other functions such as hardware and software security, amonitored operating system, cryptographic functions, peripheral control,telemetry, and/or the like. In addition, device controller 455 mayinclude technology for allowing device controller 455 to be booted in asecure manner, allowing the device to be securely updated, ensuring that“proper” software is running on the device, allowing the device tofunction correctly as an IoT device, and/or the like. Security complex451 may include the hardware root of trust of device controller 455 asthe basis for the security functions provided by device controller 455.

In some examples, flash memory 456 is an external NOR flash memory thatincludes a flash controller and dual quad serial public interface (QSPI)NOR flash devices (the two memory banks, in this example) in parallel,where each flash memory bank is a separate integrated circuit accessedvia a separate channel. However, the disclosure is not so limited, andany suitable memory configuration and/or suitable set of memories may beemployed.

During a normal boot, the processor may be booted in a secure mannerthat begins with a security complex that includes a hardware root oftrust for device controller 455. In some examples, a first bootloader isread from ROM, and a public key may be used by security complex 451 toverify that the first bootloader has been properly digitally signed. Insome examples, verifying the signature of the first bootloader is acryptographic operation that is performed in hardware. In some examples,until and unless the digital signature of the first bootloader isverified, the first bootloader is not loaded, and access to all of theflash memory banks is prevented. In some examples, once the signature ofthe first bootloader is verified, the first bootloader is loaded, andaccess to all of the flash memory banks is allowed. In some examples,further verification beyond just verification of the first bootloaderhas been signed may also be required in order to grant access to all ofthe flash memory banks. This may be used to help protect against, forexample, loading of valid older code with vulnerabilities.

In some examples, verification in order to allow access to allow thememory banks may proceeds as follows. Security complex 451 may read in aportion of one of the memory banks that is not restricted, such as thefirst memory bank in some examples. In some examples, this portion ofthe flash memory may be 16 kb, 52 kb, or the like. A hardware block insecurity complex 451 may then compare the loaded portion of thenon-restricted flash memory bank against particular hardware fuses, withverification being unsuccessful unless the loaded portion matches thefuses. Hardware keys may also be used to verify that the code is trustedcode in some examples. Comparison of a portion of the non-restrictedportion of the flash memory against hardware fuses by a hardware blockin security complex 451 may be used to prevent previously valid but nowolder code from having vulnerabilities being loaded. Fuses may beburned, along with changing the corresponding non-restricted portion offlash memory to be checked against the hardware fuses to be matched withthe fuses being updated, to prevent such older code from subsequentlybeing validated and from having access to the secrets stored in thesecure portion of the flash memory.

In some examples, flash memory 456 is a single-image memory. In someexamples, flash memory 456 has one bank. In some examples, flash memory456 has two banks, and/or other separation(s) in the memory but is stilla single-image memory in which the separations are not accessible.

In some examples, flash memory 456 is protected from corruption with anexample of an erasure coding scheme as described here. Although theerasure coding scheme is described herein with regard to flash memory456, the erasure coding schema may also be used with any suitable memoryor set of data. In some examples, the erasure coding scheme describedherein may be particular beneficial with regard to embedded devices witha single-image memory for which is desirable to protect against asignificant amount of contiguous corruption, accidental overwrite,and/or the like, and where there is not significant space to store fullback-ups. In some examples, the erasure coding scheme is used with flashmemory to protect against flash memory corruption.

In some examples, individual applications and/or pieces of firmware maybe dynamically erasure coded, using a different erasure coding schemefor each different application and/or piece of software, withflexibility based on the size of each application and/or piece offirmware being encoded.

In some examples, an erasure coding scheme may be used in which thememory is erasure coded based on consecutive stripes of a fixed size,with possibly a partial stripe left over if the memory size is notevenly divisible by the stripe size.

In some examples, an erasure coding scheme may be used in which thememory is erasure coded based on non-consecutive stripes of a fixedsize, with possibly a partial stripe left over if the memory size is notevenly divisible by the stripe size. For instance, in some examples, theerasure coding scheme may use stripes in a “checkerboard” pattern inwhich each data block is divided by the number of stripes, e.g.,striping the data blocks within a stripe among all other stripes.

In this way, in some examples, with N stripes, the first data block ofsize S is divided into N stripes, with the first S/N of data belongingto the first stripe, the next S/N of data belonging to the secondstripe, and so on, with the first S/N of the second data block being thenext S/N of data of the first stripe, and so on. In another example, fora first data block of size S is divided into N stripes, the first S/N ofdata may belong to the first block, and the second blocks data iscording to stripe size*block size*stripe number.

For instance, in one example, with a 16 MB memory with 8 MB of memorydedicated to applications, the 8 MB of applications can be erasure codedwith 64 kb stripes, using 8 k data blocks. Accordingly, in this example,there is 8 MB/64 kb stripes, which is 133 stripes. Accordingly, in thisexample, the first stripe begins with the first 8 MB/(8 kb*133) of data,the second stripe begins with the second 8 MB/(8 kb*133) of data, and soon. In this example, after the first block of each of the 133 stripes,the first stripe then continues with the next 8 MB/(8 kb*133) of data,and so on. In some examples, the offsets of each stripe is calculatedand the stripes are stitched together based on the calculated offsets,and the stripes are then input to the erasure coding algorithm. In thisway, in this example, the memory can recover from up to one continuousMB of corruption. However, the amount of corruption that can berecovered from depends on the number of erasure coding blocks generated(e.g., the chosen fault tolerance model). Also, in some examples, whiletuned for preventing corruption of contiguous portions of memory, thisdoes not prevent tolerating random corruption. For example, someinstance of random corruption can be prevented via the disclosedtechnology.

In some examples, a hash or checksum of every single data block that iserasure coded is stored. In some examples, the checksums or hashes arenot stored in the data itself, but instead there is a separate blockhash partition, file, or other data structure that tracks hashes.

A fault tolerance may be selected, with greater fault tolerancesrequiring a greater overhead. For instance, in some examples, theerasure coding algorithm tolerates two bad blocks per stripe instead ofone, with greater overhead required than if the algorithm tolerated onebad block per stripe. In some examples, there is a trade-off betweenfault tolerance and overhead.

If there is a partial stripe, e.g., a stripe with less than a fullstripes worth of data, the partial stripe can be handled in differentmanners in different examples. In some examples, phantom blocks may beused, in which the leftover blocks are zeros that are not actuallystored. This scheme may be less fault tolerant, e.g., because thepartial stripe may only be able to tolerate contiguous corruption in anamount associated with the chosen the fault tolerance mechanism chosen.Alternatively, a full back-up may be kept of the partial stripe forgreater fault tolerance.

In some examples, in the erasure code generation, the inputs are theamount of memory that is being erasure coded, the erasure coding schemeto be used, the stripe size, the block size, how to handle any partialstripes, and the fault tolerance (i.e., how many bad blocks per stripecan be recovered from).

In some examples, after receiving the inputs, for all data for whichthere is no partial stripes, the number of stripes are counted, and eachstripe is generated as discussed above, based on calculated offsets togenerate each stripe and providing the stripes to the erasure codingalgorithm. If the memory is byte-addressable NOR flash, the addressesmay be read based on the calculated offsets directly using pointers.

In some examples, the hashes are also calculated. In some examples, thehashes are calculated from another mechanism and the hashes calculatedand stored from another mechanism can be re-used by the erasure coding.

The erasure coding generation process is discussed above. If corruptionoccurs, the corrupted data may be repaired using the generated erasurecode based on an erasure coding repair process. The repair process maybe initiated based on corruption being detected in the memory, which mayoccur in various ways in various examples. In some examples, corruptionis detected in some way for a file or executable binary, such as viahash or signature verification, which may cause the repair process to beinitiated.

In some examples, in the repair process, first the bad blocks aredetermined by checking the blocks against the hashes. In some examples,along the flash range that is known to be corrupt, for each block in theflash range, the stripe that the block is in is calculated, all of theaddresses in the stripe are found, and the hash of those blocks ischecked against the known hashes for those blocks. In some examples, foreach hash that is mismatched, the corresponding block is declared to bebad for that stripe.

Next, in some examples, the number of bad blocks is compared with thefault tolerance. If there are zero bad blocks, then in some examples,the process continues to the next stripe. In some examples, if there isone or more bad blocks, and the number of bad blocks is greater than thefault tolerance, then the stripe cannot be repaired. In some examples,if there is one or more bad blocks, and the number of bad blocks is lessthan or equal to the fault tolerance, then the bad blocks are repaired,e.g., by invoking a chosen erasure coding scheme with the stripe dataand the erasure coding blocks.

In some examples, to repair a bad block, the stripe filled out is passedthrough the erasure coding algorithm along with an indication as towhich block is bad, and the pointer to the erasure coding block for thatstripe is also passed to the algorithm. In some examples, the algorithmthen returns a repaired block. In some examples, the hash to the repairblock is re-calculated, and a determination is made as to whether thehash matches the stored hash for the block. In some examples, if thereis a mismatch, then either the repair failed, or the stored block hashis bad.

In some examples, every block in the range is either repaired, orskipped because it is not corrupt, in this manner. Once this iscomplete, in some examples, a confirmation may be made as to whether therange is still corrupt. For instance, in an example in which the rangewas found corrupt based on a mismatched signature, the range can be sentto the entity that initially performed the signature check, and thatentity can check to determine whether the range is still corrupted, forexample, by re-running the signature check and conforming that theverification now passes.

The erasure code may also be updated when the data content of the memorythat is protected by the erasure coding is changed. First, in someexamples, a range of memory that is changed is input. In some examples,for each block, the erasure coding data is regenerated using the sameprocess described above for erasure code generation. In some examples,each generated erasure coding block is overwritten with the new block.

In other examples, each block in the range is compared with the storedblock hashes. In these examples, only those blocks for which the hashesdifferent have their erasure coding data regenerated, with those blocksbeing overwritten. In some examples, blocks for which the hash matchesare skipped, e.g., if the data for the block within the stripe has notchanged, then the stripe's erasure coding block is not updated.

Device updates for device controller 455 may occur frequently. Forexample, applications, other software, and/or firmware on devicecontroller 455 may be updated. An update may be composed of a set ofbinaries that are referred to as images or image binaries. In someexamples, each image binary has an associated piece of metadata calledan image metadata. In some examples, the image metadata may include thename of the image, version of the image, signature, and/or the like. Insome examples, the image metadata is stored in the cloud, e.g., makingit queryable.

In some examples, the image metadata is also embedded into the imagebinary itself, e.g., ensuring that any image binary is self-describing.This might be implemented by uploading the metadata as a separate file,with the service repackaging the image binary and metadata together.Alternatively, the metadata might be pre-packed inside of the imagebinary, and unpackaged by the service.

A hardware stock keeping unit (SKU) is used in some examples as part ofthe process of describing hardware update policy and allowing itsefficient implementation. In some examples, hardware SKUs are not aunique identifier of a single chip or device. Rather, in these examples,the hardware SKU uniquely identifies a particular configuration (color,model, capabilities, country etc.) in which a device is sold. In oneexample, the hardware SKUs for each IoT device include a device SKU anda chip SKU. In some examples, there may be more than two descriptiveSKUs such that three or more types of SKUs provide a hierarchy of threeor more levels. The chip SKU may define the particular type of chip thatis running within the IoT device and the capabilities of the chip. Aserial number, public key, or device ID may be used to uniquely identifya single instance of a chip.

The device SKU may be used as an identifier that describes a type of IoTdevice that uses a chip. The SKU might be the SKU used by a productmanufacturer that identifies a particular model and configuration in itsproduct line. Each device SKU may have a set of attributes that describefeatures that are software dependent. In addition, every device SKU mayhave an attribute describing a unique chip SKU that all devices withthis device SKU contain. These attributes may also be defined and storedin the IoT service solution within the SKU registries. The attributesmay also describe features that the manufacturer uses to differentiatemodels of IoT devices from one another (i.e., washer vs dryer, tan vs.stainless steel), but also small differences (the hardware SKU for themotor used, the type of LED panel connected to the 4×4 chip) thatcompose the IoT device. In some examples, there are two SKU registries;one registry for device SKUs and another registry for chip SKUs.

A release describes binary content that can be made available to adevice. A release is a coherent set of image binaries for some targets.In some examples, a release is composed of at least four differententities: a set of image binaries, a single SKU, a component ID, and asemantic version. In some examples, each IoT device has at least twodifferent releases installed on it. In some examples, a component IDcollects all images that apply to a single component. A release may becoherent in that a release is pre-tested to ensure that all of thebinaries in the release work together.

In some examples, releases are not made available to IoT devices untilthey are deployed. In some examples, deployments bundle a set ofreleases with a set of constraints defining the properties of devicesthe deployment is intended for. In some examples, after a deployment isregistered and activated, it is included in queries when ultimatelycalculating which releases are intended for an IoT device.

In some examples, to begin the update process, a software engineerregisters and uploads new image binaries from a local machine to an IoTupdate service associated with the IoT support service for the IoTdevices. In some examples, the uploaded image binaries should be signed,because the image binaries will only be validated if the image binariesare signed. In some examples, image signing allows each image binary tobe authenticated as being signed by a trusted entity.

In some examples, the software engineer may also define new releasesaround a particular SKU and register them with the IoT update service.The engineer may also be able to increment the release version number,compose a set of image binaries for the next version of a release,confirm that the composed image binaries meet all of the constraintsprovided by each image's metadata, and receive suggestions forconstraint-compatible image binaries. For any given release, thesoftware engineer may be able to use query tools to see the set of IoTdevices for which the release is currently used, used as a backup, ormade available. Further, the engineer may be able to query a particulardevice group and determine which set of deployments and releases thegroup is currently using.

Once a new release is defined, an engineer may target that release at aset of machines by defining a deployment. An engineer may target asingle SKU (across releases), or target all SKUs that are dependent onan image binary that was recently updated. After a deployment isactivated it may be made available to IoT devices when the IoT devicesnext check for updates. In the normal case an IoT device may make arequest for services to send it which releases it should currently haveon some regular cadence (e.g., weekly). The engineer may alsoproactively request devices immediately make this request rather than onthe regular cadence.

In some examples, the cloud services are capable of initiating bothupgrades and downgrades in the release. In some examples, the cloud canforce IoT devices to rollback to an old release. As discussed in greaterdetail below, in some examples, the IoT devices include backup copies ofprevious updates. In some examples, the cloud can force an IoT device todowngrade to a previous update release that is stored as a backup copyon the IoT device. In some examples, there is insufficient space tostore an uncompressed backup copy, and the backup copy of the last knowngood version is stored in a compressed state.

In some examples, when a release is made available to a group of IoTdevices via a deployment, it will not be made available to all IoTdevices in the group simultaneously. Instead, in these examples, eachrelease is made available in a rolling deployment. For example, arolling deployment may start by deploying to a small subset of targetedIoT devices. As updates complete successfully, the number of IoT deviceseligible for deployment increases.

In some examples, one or more of the IoT devices each include a daemonthat sends a query to a cloud service (e.g., IoT support service) as towhether or not there is a currently available new device update for theIoT device. In some examples, the daemon is included on the NW of theIoT device. Next, the NW daemon on the IoT device may receive, from thecloud service, information related to an update for the IoT device. Insome examples, the information includes an indication of the releasethat the IoT device should be on, and includes metadata associated withthe indicated release, such as the semantic version, and metadataassociated with each image binary in the indicated release such as anID, a version, and the like. In some examples, secure transmission isused in the communication between the IoT device and the cloud service.

In some cases, upon receiving the indication related to the update forthe IoT device, the IoT device validates the update. In some examples,the IoT device validates the update by validating that the update isproperly signed. In some examples, the IoT device also confirms whethera new version should be downloaded by comparing the image binaries to beinstalled for the update against what is already installed in the IoTdevice. In some examples, the IoT device then determines which imagebinaries should be downloaded from the cloud service to ultimately beinstalled as part of the update process. In some examples, for eachimage binary that the IoT device determined should be downloaded fromthe cloud service, the daemon sends a corresponding request to the cloudservice to download the image binary. In some examples, the cloudservice sends to the daemon the location of each download in response toa request for the location of each image binary, and then the daemonsends requests to the indicated locations to download each image binary.

In some examples, the IoT device then receives the requested imagebinaries from the cloud service. In some examples, there is insufficientRAM on the IoT device to store the image binaries in memory, and soinstead each image binary is streamed to the IoT device. The total setof image binaries received by the IoT device comprise a release. In someexamples, secure transmission is used between the cloud service and theIoT device. Further, in some examples, a compressed version of theupdate is downloaded, because there is insufficient space to store anuncompressed version.

Device controller 445 may be divided into a number of partitions. Insome examples, the partitions are physical partitions, and in otherexamples, the partitions are logical partitions. In the example ofdevice controller 455 illustrated in FIG. 4, the partitions are physicalpartitions including a firmware partition, an OS partition, and anapplications partition. Other suitable partitions may be employed inother examples.

In some examples, the partitions are updated atomically. In someexamples, updating a partition “atomically” means updating the partitionas a single unit, rather than completing an update to one portion of thepartition at one time and another part of the partition at another time.In some examples, particularly where there are inter-partitiondependencies, the partitions may be atomically updated in a specificorder, to ensure that a newly updated partition does not rely upon adependency on updated functionality on another partition that has yet tobe updated. In some examples, the upgrade is complete after eachpartition has been atomically upgraded, with the atomic partitionupgrades proceeding in the proper order in cases in which an order isrequired based on the inter-partition dependencies.

In some examples, partition tables are used to ensure that a partitionupgrade is tolerant to power faults and/or other failures. In someexamples, there are two partition tables in each partition, a primarypartition table and a back-up partition table. In some examples, thereare two tables because, if a power and/or other failure occurs while oneof the partition tables is being written to, the other partition tableis still valid. In some examples, each partition table has an entry foreach image on the partition, and each entry includes information aboutthe image, such as, in some examples, the offset of the image in flashmemory. The information may also include the status of the image,including whether or not the image has been installed. In some examples,the table uses some mechanism, such as a hash, to determine whether thetable is consistent or corrupted.

In some examples, atomically updating a partition may be accomplished asfollows.

After the version has been downloaded, the installation is staged. Afterthe installation has been staged, the updated version is written to thepartition. Next, the updated version is verified. After the updatedversion is verified, the current partition table is copied to memory.The original entry pointing to the original version is deleted, and thena new entry pointed to the current version is added to the copy. At thispoint, the copy is now the updated partition table. The updatedpartition table is then written to the back-up partition table. Then atthe next boot, the updated partition table is written to the primarypartition table. Next, a boot health check is performed. If the boothealth check succeeds, then the update to the partition is complete. Ifthe boot health check fails, the following actions are taken. If theprimary partition table is corrupt, then the primary partition table isoverwritten with the backup partition table. If the backup partitiontable is corrupt, then the backup partition table is overwritten withthe primary partition table. If neither the primary partition table northe secondary partition table is corrupt, but the primary partitiontable and secondary partition table different from each other, thisindicates that there was a power fault and/or other failure between thewriting of the primary partition table and the secondary partitiontable, and so the primary partition table is then overwritten with theback-up partition table. If the primary partition table and the backuppartition table are both corrupt, then either the partition tables arecorrected through as other method, such as erasure coding, as discussedin greater detail below, or the upgrade fails.

The method above describes an example of an image update when sufficientfree space exists for the updated version. If sufficient free space forthe updated version does not exist, the following steps may first beperformed.

First, a memory allocator is used to determine the offset of each imagein flash in the partition. Next, in memory, a virtual layout is created.The virtual layout is used to determine whether there is sufficienttotal room in the flash memory, but the free space is fragmented. Insome examples, if there is not sufficient room in the flash memory, eventaking into account the fragmented space—in this case, the update fails.

If, however there is sufficient space when taking into account thefragmented space, then images not being updated may be copied to thebackup partition. Next an empty table may be written to flash to boththe primary partition table and the backup partition table. If a powerand/or other failure occurs after writing the empty tables, installationcan simply pick up where it left off after the first time.

Next, the images not being updated may be copied back into flash memoryalong with the new images to be updated, packing the images tightly. Thesteps may then proceed as they normally would.

Although the memory allocator is discussed above to be used in whenthere is insufficient free space, in some examples, the memory allocatortracks the free space available in each case.

The above discussion describes a method of updating that is tolerant topower, and other, failures. In some examples, the partition tables mayalso be protected from corruption with erasure coding. A hash may betaken of each partition table, and the hash may be used to detectcorruption to a partition table. In some examples, in order to upgrade apartition in a way that is protected from both failures and corruption,the erasure coding blocks are also be updated, and in the correct order.

One example of an update method that is also tolerant to corruption isas follows.

First, the installation is staged. Next, the primary and back-uppartition tables are both modified to install to add indication that aninstallation is in progress. In some examples, this indication is an“install in progress” entry in the primary partition table and theback-up partition table. The “install in progress” entry includes therange of data that is being modified during the install.

In some examples, after adding the install in progress entry to bothtables, the backup partition table is written, so that the backuppartition table includes entries for installation targets and/or thelike. In some examples, next, the erasure code for the back-up partitiontable is regenerated, and a hash is generated for the back-up partitiontable. In some examples, next, the primary partition table is written,the erasure code for the primary partition table is regenerated, and ahash is generated for the primary partition table. Additionally, in someexamples, a hash is generated for every block in the partition, andstored in a separate area of flash memory that tracks block hashes.

In some examples, if at any time the back-up partition is successfullywritten and not the primary partition table, as indicated by the primaryand back-up partition tables not matching, if there is an install inprogress entry, then all of the erasure coding blocks described by theinstall in progress entry within the range of data specified in theinstall in progress entry are regenerated, and then the erasure codingblocks for the partition tables are regenerated as well.

In some examples, next, as discussed above, if sufficient free space forthe updated version does not exist, the steps discussed above may beperformed. In some examples, after those steps, or skipping those stepsis there is already sufficient free space in memory, the updated versionis written to the partition. In some examples, next, the updated versionis verified.

In some examples, after the updated version is verified, the erasurecoding blocks are updated for the images. In some examples, the hashesare also updated. In some examples, next, the install in progress entryis removed from both partition tables.

In some examples, next, the current partition table is copied to memory.In some examples, the original version of the partition table is deletedfrom the copy, and the then the current version is added to the copy. Insome examples, at this point, the copy is now the updated partitiontable. In some examples, the updated partition table is then written tothe back-up partition table. In some examples, the erasure coding blockfor the back-up partition table is then updated. In some examples, thehash of the back-up partition table is then updated.

In some examples, the updated partition table is written to the primarypartition table after the device next boots.

In some examples, next, a boot health check is performed, with the stepsproceeds as in the previous example after the boot health check isperformed. If both the primary partition table and the backup partitiontable are corrupt, some other repair methods such as erasure code repairmay be used.

In some examples, the erasure coding block for the back-up partitiontable is then updated. In some examples, the hash of the back-uppartition table is then updated.

Device controller 445 illustrates but one specific example of a devicein which the disclosed fault tolerant update method may be performed. Inother examples, the disclosed fault tolerant update method may beperformed in other suitable devices.

Illustrative Processes

For clarity, the processes described herein are described in terms ofoperations performed in particular sequences by particular devices orcomponents of a system. However, it is noted that other processes arenot limited to the stated sequences, devices, or components. Forexample, certain acts may be performed in different sequences, inparallel, omitted, or may be supplemented by additional acts orfeatures, whether or not such sequences, parallelisms, acts, or featuresare described herein. Likewise, any of the technology described in thisdisclosure may be incorporated into the described processes or otherprocesses, whether or not that technology is specifically described inconjunction with a process. The disclosed processes may also beperformed on or by other devices, components, or systems, whether or notsuch devices, components, or systems are described herein. Theseprocesses may also be embodied in a variety of ways. For example, theymay be embodied on an article of manufacture, e.g., asprocessor-readable instructions stored in a processor-readable storagemedium or be performed as a computer-implemented process. As analternate example, these processes may be encoded asprocessor-executable instructions and transmitted via a communicationsmedium.

FIGS. 5A-5B illustrate an example dataflow for a process (580). In someexamples, process 580 is performed by device controller, e.g., devicecontroller 445 of FIG. 4. In other examples, processor 580 may beperformed in other suitable devices. In some examples, in process 580, apartition of a memory is atomically updated, as illustrated by steps481-487. In some examples, the partition includes partition tablesincluding a primary partition table and a back-up partition table. Insome examples, the partition tables include entries for the imagesincluded in the partition, and information associated with the imagesincluded in the partition.

In the illustrated example, step 581 occurs first. At step 581, in someexamples, an updated version is written to the partition. As shown, step582 occurs next in some examples. At step 582, in some examples, thewritten updated version is verified. As shown, step 583 occurs next insome examples. At step 583, in some examples, an updated partition tableis written to the back-up partition table. As shown, step 584 occursnext in some examples. At step 584, in some examples the updatedpartition table is written to the primary partition table.

As shown, decision step 585 occurs next in some examples. At decisionstep 585, in some examples, a determination is made as to whether apower fault and/or other failure occurred while the primary partitiontable was being written. If not, the process may then proceed to thereturn block, where other processing is resumed.

If instead, at decision step 585, it is determined that a power faultand/or other failure occurred while the primary partition table wasbeing written, step 586 occurs next. At step 586, in some examples, theprimary partition table is overwritten with the back-up partition table.The process may then proceed to the return block.

CONCLUSION

While the above Detailed Description describes certain examples of thetechnology, and describes the best mode contemplated, no matter howdetailed the above appears in text, the technology can be practiced inmany ways. Details may vary in implementation, while still beingencompassed by the technology described herein. As noted above,particular terminology used when describing certain features or aspectsof the technology should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects with which that terminology is associated. Ingeneral, the terms used in the following claims should not be construedto limit the technology to the specific examples disclosed herein,unless the Detailed Description explicitly defines such terms.Accordingly, the actual scope of the technology encompasses not only thedisclosed examples, but also all equivalent ways of practicing orimplementing the technology.

We claim:
 1. An apparatus comprising: a device including at least onememory having processor-executable code stored therein, and at least oneprocessor that is adapted to execute the processor-executable code,wherein the processor-executable code includes processor-executableinstructions that, in response to execution, enable the device toperform actions including: atomically updating a partition of a memory,wherein the partition includes images and partition tables; thepartition tables simultaneously include a primary partition table and aback-up partition table; the partition tables each include, for eachimage of the images included in the partition, an entry that includesinformation associated with the image, including a memory offset of theimage; and wherein atomically updating the partition of the memoryincludes: writing an updated partition version to the partition;verifying the written updated partition version; creating an updatedpartition table; writing the updated partition table to the back-uppartition table; writing the updated partition table to the primarypartition table after booting the device; making a determination as towhether a power fault occurred while the primary partition table wasbeing written; and if it is determined that the power fault occurredwhile the primary partition table was being written overwriting theprimary partition table with the back-up partition table.
 2. Theapparatus of claim 1, wherein atomically updating the partition of thememory further includes: performing a boot health check; if it isdetermined that the primary partition table is corrupt and the back-uppartition table is not corrupt overwrite the primary partition tablewith the back-up partition table; and if it is determined that theback-up partition table is corrupt and the primary partition table isnot corrupt overwrite the back-up partition table with the primarypartition table; if it is determined that the primary partition table isnot corrupt and the back-up partition table is not corrupt and theprimary partition table is different than the back-up partition tableoverwrite the primary partition table with the back-up partition table.3. The apparatus of claim 1, the actions further including: atomicallyupdating another partition of the memory.
 4. The apparatus of claim 1,wherein writing the updated partition table to the back-up partitiontable includes: copying a current primary partition table to the memory;modifying the copy of the current primary partition table by deleting anentry corresponding to a current partition version from the primarypartition table; further modifying the modified copy of the currentprimary partition table by adding the updated partition version as a newentry to the modified copy of the current primary partition table; andwriting the further modified copy to the back-up partition table.
 5. Theapparatus of claim 1, wherein atomically updating the partition furtherincludes: downloading the updated partition version.
 6. The apparatus ofclaim 1, wherein the partition of the memory is a physical partition ofthe memory.
 7. The apparatus of claim 1, wherein atomically updating thepartition further includes: copying each image in the partition that isnot to be updated to a back-up partition; writing an empty table to theback-up partition table; writing an empty table to the primary partitiontable; and writing the copied images back to the partition along withthe updated partition version.
 8. The apparatus of claim 7, whereinatomically updating the partition further includes: using a memoryallocator to determine an offset of each image in the partition; andcreating a virtual layout of the partition.
 9. The apparatus of claim 1,wherein atomically updating the partition further includes: storingerasure coding blocks for the partition; before writing the updatedpartition version to the partition, adding an indication of aninstallation in progress to the primary partition table and the back-uppartition table, and further indicating a range of the installation; ifit is determined that the primary partition table does not match theback-up partition table, and the partition tables indicate aninstallation in progress using the erasure coding blocks to regeneratethe range of the installation indicated by the indication of theinstallation in progress.
 10. The apparatus of claim 9, whereinatomically updating the partition further includes: after verifying thewritten updated partition version, updating the erasure coding blocksfor the partition.
 11. An apparatus comprising: a device including atleast one memory having processor-executable code stored therein, and atleast one processor that is adapted to execute the processor-executablecode, wherein the processor-executable code includesprocessor-executable instructions that, in response to execution, enablethe device to perform actions including: storing erasure coding blocksfor a partition of a memory, wherein the partition includes partitiontables including a primary partition table and a back-up partitiontable; the partition tables include entries for images included in thepartition, and information associated with the images included in thepartition; and atomically updating the partition of the memory,including: adding an indication of an installation in progress to theprimary partition table and the back-up partition table, and furtherindicating a range of the installation; writing the back-up partitiontable; generating erasure code for the back-up partition table;generating a hash for the back-up partition table; writing the primarypartition table; generating erasure code for the primary partitiontable; generating a hash for the primary partition table; writing anupdated partition version to the partition; verifying the writtenupdated partition version; writing updated erasure code for the updatedpartition version; writing updated data hashes for the updated partitionversion; writing an updated partition table to the back-up partitiontable; updating the erasure code for the back-up partition table;generating a new hash for the back-up partition table; writing theupdated partition table to the primary partition table; updating theerasure code for the primary partition table; and generating a new hashfor the primary partition table.
 12. The apparatus of claim 11, whereinatomically updating the partition further includes: if it is determinedthat the primary partition table does not match the back-up partitiontable, and the partition tables indicate an installation in progressusing the erasure coding blocks to regenerate the range of theinstallation indicated by the indication of the installation inprogress.
 13. The apparatus of claim ii, wherein atomically updating thepartition further includes: copying each image in the partition that isnot to be updated to a back-up partition; writing an empty table to theback-up partition table; writing an empty table to the primary partitiontable; and writing the copied images back to the partition.
 14. Theapparatus of claim ii, wherein atomically updating the partition furtherincludes: after verifying the written updated partition version,updating the erasure coding blocks for the partition.
 15. The apparatusof claim ii, wherein atomically updating the partition further includes:after adding the indication of the installation in progress, and beforewriting the updated partition version: writing the back-up partitiontable; generating the erasure code for the back-up partition table;generating the hash for the back-up partition table; writing the primarypartition table; generating the erasure code for the primary partitiontable; and generating the hash for the primary partition table.
 16. Amethod comprising: writing an updated partition version to a partitionof a memory of a device, wherein the partition includes image binaries,and further includes partition tables simultaneously including a primarypartition table and a back-up partition table; the partition tables eachinclude, for each image binary of the image binaries included in thepartition, an entry that includes information associated with the imagebinary including a memory offset of the image binary; checking avalidity of the written updated partition version; creating an updatedpartition table; writing, in the back-up partition table, the updatedpartition table; writing, in the primary partition table, the updatedpartition table after booting the device; running a boot health check;making a determination as to whether a fault occurred while the primarypartition table was being written; and if it is determined that thefault occurred while the primary partition table was being writtenoverwriting the primary partition table with the back-up partitiontable.
 17. The method of claim 16, further comprising copying each imagebinary in the partition that is not to be updated to a back-uppartition; writing an empty table to the back-up partition table;writing an empty table to the primary partition table; and writing thecopied image binaries back to the partition.
 18. The method of claim 16,further comprising storing erasure coding blocks for the partition;before writing the updated partition version to the partition, adding anindication of an installation in progress to the primary partition tableand the back-up partition table, and further indicating a range of theinstallation; and if the partition tables indicate an installation inprogress using the erasure coding blocks to regenerate the range of theinstallation indicated by the indication of the installation inprogress.
 19. The method of claim 18, further comprising after checkingthe validity of the written updated partition version, updating theerasure coding blocks for the partition.
 20. The method of claim 18,further comprising after adding the indication of the installation inprogress, and before writing the updated partition version: writing theback-up partition table; generating erasure code for the back-uppartition table; generating a hash for the back-up partition table;writing the primary partition table; generating erasure code for theprimary partition table; and generating a hash for the primary partitiontable.